Add pushing the image to GitHub registry

.github/workflows/docker-image.yml

@@ -6,13 +6,41 @@ on:
   pull_request:
     branches: [ master ]
 
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository }}
+
 jobs:
 
-  build:
+  build-and-push-image:
 
     runs-on: ubuntu-latest
 
+    permissions:
+      contents: read
+      packages: write
+
     steps:
-    - uses: actions/checkout@v2
-    - name: Build the Docker image
-      run: docker build . --file Dockerfile --tag alice-lg:$(date +%s)
+      - name: Checkout repository
+        uses: actions/checkout@v2
+
+      - name: Log in to the Container registry
+        uses: docker/login-action@f054a8b539a109f9f41c372932f1ae047eff08c9
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Extract metadata (tags, labels) for Docker
+        id: meta
+        uses: docker/metadata-action@98669ae865ea3cffbcbaa878cf57c20bbf1c6c38
+        with:
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+
+      - name: Build and push Docker image
+        uses: docker/build-push-action@ad44023a93711e3deb337508980b4b5e9bcdc5dc
+        with:
+          context: .
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}